The field of the invention is oil and gas well equipment. In oil and gas wells, sand or similar particulate material is often mixed with water and injected into the well under high pressure. The pressurized liquid helps to fracture underground formations around the well bore. This allows oil and/or gas in the underground formations to flow more freely to the well bore. The fracturing is achieved hydraulically via pumping the liquid into the well under high pressure. The sand acts a proppant to hold the underground fractures open after the water is removed.
As pressure on the well bore is released, the injected water returns back up and out of the well. For environmental and other reasons, the return water is captured and held in a holding reservoir or tank. The return water may then be reused in the fracturing process. The return water however typically contains a substantial amount of sand. The sand must be separated from the water. Various so-called sand trap or de-sanding apparatus have been developed for this purpose. However, these existing designs have various disadvantages in performance, efficiency, utility, cost or other factors. Accordingly, an improved sand separator is needed.